A new crack has appeared within Spain's conservative ruling party over government legislation to ban women from freely choosing abortion.

Prime Minister Mariano Rajoy's government has come under fire from the opposition after announcing just before Christmas it would roll back a 2010 law that had allowed women to opt freely for abortion in the first 14 weeks of pregnancy.

The legislation, yet to pass parliament where the ruling Popular Party enjoys an absolute majority, would allow abortion only in cases of rape or a threat to the physical or psychological health of the mother.

But signs of dissent also emerged from within the ruling party itself.

"No-one can deny anyone the right to be a mother and no-one can oblige anyone to a be mother either," José Antonio Monago, the Popular Party head of government in the western region of Extremadura, said in an end-of-year address on Monday.

"Extremadura supports a reform of the abortion law by consensus," he added.

"The message to the people of Extremadura is clear and firm: remove any ideological dimension from fundamental matters," he said, in a reference to health and education.

The Popular Party head of the Galicia regional government, Alberto Núñez Feijóo, has also called for the abortion bill to be changed to win broader support.

Cristina Cifuentes, the government's representative in the region of Madrid, has said she favours allowing women a certain period in which to carry out terminations.

She has also said, however, that a reform of the 2010 law was necessary, in part because it formed a campaign promise by the Popular Party ahead of the 2011 elections that brought it to power.